期刊
AGRICULTURAL AND FOREST METEOROLOGY
卷 205, 期 -, 页码 11-22出版社
ELSEVIER
DOI: 10.1016/j.agrformet.2015.02.007
关键词
Net ecosystem exchange; Interannual variability; Biotic effect; Climatic effect; Relative importance; Climatic stress
资金
- National Natural Science Foundation of China [31290221, 31070407, 31370489]
- National Basic Research Program (973 Program) of China [2010CB833502]
- Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning
- 'Thousand Young Talents' Program in China
Interannual variability (IAV, represented by standard deviation) in net ecosystem exchange of CO2 (NEE) is mainly driven by climatic drivers and biotic variations (i.e., the changes in photosynthetic and respiratory responses to climate), the effects of which are referred to as climatic (CE) and biotic effects (BE), respectively. Evaluating the relative contributions of CE and BE to the IAV in carbon (C) fluxes and understanding their controlling mechanisms are critical in projecting ecosystem changes in the future climate. In this study, we applied statistical methods with flux data from 65 sites located in the Northern Hemisphere to address this issue. Our results showed that the relative contribution of BE (CnBE) and CE (CnCE) to the IAV in NEE was 57%+/- 14% and 43%+/- 14%, respectively. The discrepancy in the CnBE among sites could be largely explained by water balance index (WBI). Across water-stressed ecosystems, the CnBE decreased with increasing aridity (slope =0.18%mm(-1)). In addition, the CnBE tended to increase and the uncertainty reduced as timespan of available data increased from 5 to 15 years. Inter-site variation of the IAV in NEE mainly resulted from the IAV in BE (72%) compared to that in CE (37%). Interestingly, positive correlations between BE and CE occurred in grasslands and dry ecosystems (r> 0.45, P< 0.05) but not in other ecosystems. These results highlighted the importance of BE in determining the IAV in NEE and the ability of ecosystems to regulate C fluxes under climate change might decline when the ecosystems experience more severe water stress in the future. (C) 2015 Elsevier B.V. All rights reserved.
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